A conventional set-top box (STB) is used to convert an analog television signal within a radio-frequency (RF) carrier to a baseband frequency suitable for use by other conventional items such as televisions, video tape recorders and audio equipment. The STB accomplishes the RF-to-baseband conversion as a series of smaller conversions. The RF carrier is first frequency converted to an intermediate frequency signal. The intermediate frequency signal is then demodulated to produce the analog television signal at baseband. The analog television signal is filtered to separate a baseband video signal and a modulated audio signal. The modulated audio signal is demodulated to extract a baseband audio signal in an analog domain for presentation external to the STB.
The STBs commonly perform enhancement processing of the baseband video and audio signals. For example, graphic overlays are provided in the video signal and sound quality adjustments are made to the audio signal. The enhancement processing is conventionally performed in a digital domain using a digital signal processor. The baseband audio and video signals are digitized, processed, and then converted back to the analog domain for presentation. The result is a significant amount of analog circuitry in the STB to transform the RF carrier to a digitized video signal and a digitized audio signal prior to the enhancement processing.